2014 Tulelake Onion Weed Control Updates. Rob Wilson IREC Director/Farm Advisor

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1 2014 Tulelake Onion Weed Control Updates Rob Wilson IREC Director/Farm Advisor

2 Thank You California Garlic and Onion Research Advisory Board Tulelake Grower Cooperators IREC Staff and Interns Sensient Technologies and Olam International Chemical Companies

3 2014 Weed Control Study Study Objectives: Evaluate weed control and crop safety for Prowl H 2 0 applied immediately after planting, at 75% radical development, and at the loop stage on multiple Tulelake soil types Determine if the 24c delayed preemergence Prowl H 2 0 label in OR and WA has a fit for Northern California growers

4 Prowl H20 Water-based micro-encapsulated formulation of pendimethalin Generic products are now available Seedling Growth Inhibitor Controls several annual grass weeds Controls or suppresses several broadleaves including pigweed, henbit, kochia, lambsquarter, and purslane

5 Application at Planting

6 Application at 75% radical emergence

7 Application at Loop

8 Loop Stage

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10 Did Prowl Reduce Onion Stands or Reduce Early Season Onion Vigor?

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12 Weed Control Results All trials at IREC included a postemergence weed control program applied over the entire trial area GoalTender (3-4 fl. oz/a) at 1.5 leaf stage Goal 2XL (4 fl. oz/a) + Buctril (8 fl. oz/a) at 2.5 leaf stage All trials in grower fields included the grower s normal postemergence weed control program

13 2013 Trial at IREC

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15 2012 Trial on Sandy Loam Soil

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17 2014 Weed Control Results Sites in four commercial fields

18 Planted on May 1 st Sandy Loam Field 1 At planting treatments applied on May 2 nd (1 st irrigation occurred shortly after planting) 75% radical emergence treatments applied on May 12 th (10 days after 1 st irrigation) Grower applied glyphosate on May 14 th Loop treatments applied on May 19 th (17 days after planting)

19 4-5 leaf stage Roundup applied immediately before emergence

20 Prowl H pt/a + Dacthal 2.5 pt/a at 75% radical emergence Dacthal 2.5 pt/a at planting

21 Result Summary for Site 1 All Prowl H20 and Dacthal treatments improved control of lambsquarters Prowl H20 helped with nightshade control when applied at 75% radical emergence or loop stage (Goal & Buctril were the treatments that actually killed the nightshade) Prowl H20 and Dacthal treatments at planting delayed nightshade emergence reducing the # of emerged weeds before the glyphosate application

22 Planted on April 11 th Sandy Loam Field 2 At planting treatments applied on April 11 th (1 st irrigation occurred shortly after planting) 75% radical emergence treatments applied on April 18 th (7 days after 1 st irrigation) Grower did NOT apply glyphosate Loop treatments applied on April 30 th (19 days after planting)

23 4-5 leaf stage Roundup was NOT applied immediately before emergence

24 Large difference between the untreated and all Prowl H20 treatments

25 4-5 leaf stage Roundup was NOT applied immediately before emergence

26 Result Summary for Site 2 All treatments improved control of lambsquarter Weed control differences between application timings were not as evident as at Site 1 There was no statistical difference in nightshade control between all Prowl H20 treatments Dacthal and Prowl H20 treatments at 75% radical emergence and Prowl H20 at 2 pt/a at all application times resulted in the best control of common mallow and pigweed

27 High Organic Matter Silty Clay Loam Field 3 Planted on April 14th At planting treatments applied on April 15th (1 st irrigation occurred shortly after planting) 75% radical emergence treatments applied on April 29th (14 days after 1 st irrigation) Grower applied glyphosate on May 2 nd Loop treatments applied on May 5 th (22 days after planting)

28 4-5 leaf stage 1.5 pt/a 3.0 pt/a 1.5 pt/a 1.5 pt/a 1.5 pt/a 3.0 pt/a 3.0 pt/a 1.5 pt/a 1.5 pt/a No statistical difference between treatments- A lot of variability in weed pressure between plots Roundup was applied shortly before onion emergence

29 Result Summary for Site 3 No statistical difference between treatments Were the rates of Prowl H20 too low for soil type? Some treatments applied immediately after planting appeared to delay emergence of pigweed preventing control with glyphosate Treatments at planting thinned the pigweed population very early and those pigweed plants that survived were larger and difficult to control with Goal The grower s Goal program failed to kill pigweed

30 Planted on April 15th Silty Loam Field 4 At planting treatments applied on April 16th (1 st irrigation occurred shortly after planting) 75% radical emergence treatments applied on April 28th (12 days after 1 st irrigation) Grower applied glyphosate on May 1 st Loop treatments applied on May 6 th (21 days after planting)

31 4-5 leaf stage Roundup was applied shortly before onion emergence. Roundup timing was perfect and killed most weeds!

32 No statistical difference in yield

33 Weed Study Summary Prowl H20 was safe on onions at all sites Application at 75% radical emergence seemed to be the best universal application timing but more research is needed Prowl H20 provided variable control of lambsquarter, pigweed, and nightshade depending on the soil type and grower s herbicide program Higher rates may be needed on silty clay loam soils

34 Questions Reports available at: irec.ucanr.edu

35 2014 White Rot Study DADS and Garlic Juice Treatments were applied Spring 2013 Wheat was grown Summer 2013 Onions were planted Spring 2014 Fungicides were applied in-furrow at planting in 2014 No Fungicides were applied after planting

36 No visual differences until late August

37 Big Differences started to appear in Late August and September

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42 Untreated

43 Diseased Bulbs

44 TebuStar 21 fl.oz/a

45 DADS + Tebustar 21 fl. oz/a

46 Demand DADS How many acres in California are a candidate for DADS treatment? How many acres would growers be willing shank-apply DADS if they were confident the treatment would allow production of a profitable crop? What is an acceptable treatment cost per acre?